High entropy oxides (HEOs) with ideal element tunability and enticing entropy-driven stability have exhibited unprecedented application potential in electrochemical lithium storage. However, the general control of dimension and morphology remains a major challenge. Here, scalable HEO morphology modulation is implemented through a salt-assisted strategy, which is achieved by regulating the solubility of reactants and the selective adsorption of salt ions on specific crystal planes. The electrochemical properties, lithiation mechanism, and structure evolution of composition- and morphology-dependent HEO anode are examined in detail. More importantly, the potential advantages of HEOs as electrode materials are evaluated from both theoretical and experimental aspects. Benefiting from the high oxygen vacancy concentration, narrow band gap, and structure durability induced by the multi-element synergy, HEO anode delivers desirable reversible capacity and reaction kinetics. In particular, Mg is evidenced to serve as a structural sustainer that significantly inhibits the volume expansion and retains the rock salt lattice. These new perspectives are expected to open a window of opportunity to compositionally/morphologically engineer high-performance HEO electrodes.

Interfacial imperfections between the perovskite layer and the electron transport layer (ETL) in perovskite solar cells (PSCs) can lead to performance loss and negatively influence long-term operational stability. Here, we introduce an interface engineering method to modify the interface between perovskite and ETL by using multifunctional carbon dots (CDs). C=O in the CDs can chelate with the uncoordinated Pb2+ in the perovskite material, inhibit interfacial recombination, and enhance the performance and stability of device. In addition, –OH in CDs forms hydrogen bonds with I− and organic cation in perovskite, inhibiting light-induced I2 release and organic cation volatilization, causing irreversible degradation of perovskite films, thereby enhancing the long-term operational stability of PSCs. Consequently, we achieve the champion inverted device with an efficiency of 24.02%. The CDs-treated PSCs exhibit high operational stability, and the maximum power point tracking only attenuates by 12.5% after 1000 h. Interfacial modification engineering supported by multifunctional quantum dots can accelerate the road to stable PSCs.

The development of lithium-sulfur (Li-S) battery as one of the most attractive energy storage systems among lithium metal batteries is seriously hindered by low sulfur utilization, poor cycle stability and uneven redeposition of Li anode. It is necessary to propose strategies to address the problems as well as improve the electrochemical performance. One of the effective solutions is to improve the sulfiphilicity of sulfur cathode and the lithiophilicity of the Li anode. Herein, we reported that a synergistic functional separator (graphene quantum dots (GQDs)-polyacrylonitrile (PAN) @polypropylene (PP) separator) improved the electrochemical activity of sulfur cathode as well as the stability of Li anode. GQDs induced uniform Li+ nucleation and deposition, which slowed down the passivation of Li anode and avoided short-circuit. Further, three-dimensional network constructed by electrospinning nanofibers and the polar functional groups of GQDs could both effectively inhibit the shuttle of LiPSs and improve the sulfur utilization. The stability of Li-S battery was improved by the synergistic effect. In addition, GQDs and electrospinning nanofibers protector increased lifetime of separators. Benefiting from the unique design strategy, Li//Li symmetric battery with GQDs-PAN@PP separators exhibited stably cycling for over 600 h. More importantly, the Li-S full batteries based GQDs-PAN@PP separators enabled high stability and desirable sulfur electrochemistry, including high reversibility of 558.09 mA·h g−1 for 200 cycles and durable life with a low fading rate of 0.075% per cycle after 500 cycles at 0.5 C. Moreover, an impressive areal capacity of 3.23 mA·h cm−2 was maintained under high sulfur loading of 5.10 mg cm−2. This work provides a new insight for modification separator to improve the electrochemical performance of Li-S/Li metal batteries.

Electrochemical CO2 reduction into energy-carrying compounds, such as formate, is of great importance for carbon neutrality, which however suffers from high electrical energy input and liquid products crossover. Herein, we fabricated self-supported ultrathin NiCo layered double hydroxides (LDHs) electrodes as anode for methanol electrooxidation to achieve a high formate production rate (5.89 mmol h–1 cm–2) coupled with CO2 electro-reduction at the cathode. A total formate faradic efficiency of both anode for methanol oxidation and cathode for CO2 reduction can reach up to 188% driven by a low cell potential of only 2.06 V at 100 mA cm–2 in membrane-electrode assembly (MEA). Physical characterizations demonstrated that Ni3+ species, formed on the electrochemical oxidation of Ni-containing hydroxide, acted as catalytically active species for the oxidation of methanol to formate. Furthermore, DFT calculations revealed that ultrathin LDHs were beneficial for the formation of Ni3+ in hydroxides and introducing oxygen vacancy in NiCo-LDH could decrease the energy barrier of the rate-determining step for methanol oxidation. This work presents a promising approach for fabricating advanced electrodes towards electrocatalytic reactions.

Hydrogenase is a paradigm of highly efficient biocatalyst for H2 production and utilization evolved in nature. A dilemma is that despite the high activity and efficiency expected for hydrogenases as promising catalysts for the hydrogen economy, the poor oxygen tolerance and low yield of hydrogenases largely hinder their practical application. In these years, the enigmas surrounding hydrogenases regarding their structures, oxygen tolerance, mechanisms for catalysis, redox intermediates, and proton-coupled electron transfer schemes have been gradually elucidated; the schemes, which can well couple hydrogenases with other highly efficient (in)organic and biological catalysts to build novel reactors and drive valuable reactions, make it possible for hydrogenases to find their niches. To see how scientists put efforts to tackle this issue and design novel reactors in the fields where hydrogenases play crucial roles, in this review, recent advances were summarized, including different strategies for protecting enzyme molecules from oxygen, enzyme-based assembling systems for H2 evolution in the photoelectronic catalysis, enzymatic biofuel cells for H2 utilization and storage and the efficient electricity-hydrogen-carbohydrate cycle for high-purity hydrogen and biofuel automobiles. Limitations and future perspectives of hydrogenase-based applications in H2 production and utilization with great impact are discussed. In addition, this review also provides a new perspective on the use of biohydrogen in healthcare beyond energy.

Nucleophile oxidation reaction (NOR), represented by ethanol oxidation reaction (EOR), is a promising pathway to replace oxygen evolution reaction (OER). EOR can effectively reduce the driving voltage of hydrogen production in direct water splitting. In this work, large current and high efficiency of EOR on a Ni, Fe layered double hydroxide (NiFe-LDH) catalyst were simultaneously achieved by a facile fluorination strategy. F in NiFe-LDH can reduce the activation energy of the dehydrogenation reaction, thus promoting the deprotonation process of NiFe-LDH to achieve a lower EOR onset potential. It also weakens the absorption of OH− and nucleophile electrooxidation products on the surface of NiFe-LDH at a higher potential, achieving a high current density and EOR selectivity, according to density functional theory calculations. Based on our experiment results, the optimized fluorinated NiFe-LDH catalyst achieves a low potential of 1.386 V to deliver a 10 mA cm−2 EOR. Moreover, the Faraday efficiency is greater than 95%, with a current density ranging from 10 to 250 mA cm−2. This work provides a promising pathway for an efficient and cost-effective NOR catalyst design for economic hydrogen production.

The continued increase in population and the industrial revolution have led to an increase in atmospheric carbon dioxide (CO2) concentration. Consequently, developing and implementing effective solutions to reduce CO2 emissions is a global priority. The electrochemical CO2 reduction reaction (CO2RR) is strongly believed to be a promising alternative to fossil fuel-based technologies for the production of value-added chemicals. So far, the implementation of CO2RR is hindered by associated electrochemical reactions, such as low selectivity, hydrogen evolution reaction (HER), and additional overpotential induced in some cases. As a result, it is necessary to conduct a timely evaluation of the state-of-the-art strategies in CO2RR, with a focus on the engineering of the electrocatalytic systems. Catalyst morphology is one factor that plays a critical role in overcoming these drawbacks and significantly contributes to enhancing product selectivity and Faradaic efficiency (FE). This review article summarizes the recent advances in the rational design of electrocatalysts with various morphologies and the influence of these morphologies on CO2RR. To compare literature findings in a meaningful way, the article focuses on results reported under a well-defined period and considers the first three rows of the d-block metal catalysts. The discussion typically covers the design of nanostructured catalysts and the molecular-level understanding of morphology-performance relationship in terms of activity, selectivity, and stability during CO2 electrolysis. Among others, it would be convenient to recommend a comprehensive discussion on the morphologies of single metals and heterostructures, with a detailed emphasis on their impact on CO2 conversion.

The supercapacitor electrode materials suffer from structure pulverization and sluggish electrode kinetics under high current rates. Herein, a unique NiMoO4@Co-B heterostructure composed of highly conductive Co-B nanoflakes and a semiconductive NiMoO4 nanorod is designed as an electrode material to exert the energy storage effect on supercapacitors. The formed Mott-Schottky heterostructure is helpful to overcome the ion diffusion barrier and charge transfer resistance during charging and discharging. Moreover, this crystalline-amorphous heterogeneous phase could provide additional ion storage sites and better strain adaptability. Remarkably, the optimized NiMoO4@Co-B hierarchical nanorods (the mass ratio of NiMoO4/Co-B is 3:1) present greatly enhanced electrochemical characteristics compared with other components, and show superior specific capacity of 236.2 mA h g-1 at the current density of 0.5 A g -1, as well as remarked rate capability. The present work broadens the horizons of advanced electrode design with distinct heterogeneous interface in other energy storage and conversion field.

The strong metal-support interaction inducing combined effect plays a crucial role in the catalysis reaction. Herein, we revealed that the combined advantages of MoSe2, Ru, and hollow carbon spheres in the form of Ru nanoparticles (NPs) anchored on a two-dimensionally ordered MoSe2 nanosheet-embedded mesoporous hollow carbon spheres surface (Ru/MoSe2@MHCS) for the largely boosted hydrogen evolution reaction (HER) performance. The combined advantages from the conductive support, oxyphilic MoSe2, and Ru active sites imparted a strong synergistic effect and charge redistribution in the Ru periphery which induced high catalytic activity, stability, and kinetics for HER. Specifically, the obtained Ru/MoSe2@MHCS required a small overpotential of 25.5 and 38.4 mV to drive the kinetic current density of 10 mA cm−2 both in acid and alkaline media, respectively, which was comparable to that of the Pt/C catalyst. Experimental and theoretical results demonstrated that the charge transfer from MoSe2 to Ru NPs enriched the electronic density of Ru sites and thus facilitated hydrogen adsorption and water dissociation. The current work showed the significant interfacial engineering in Ru-based catalysts development and catalysis promotion effect understanding via the metal-support interaction.

Boosting of rechargeable lithium metal batteries (LMBs) holds challenges because of lithium dendrites germination and high-reactive surface feature. Separators may experience structure-determined chemical deterioration and worsen Li plating-stripping behaviors when smoothly shifting from lithium-ion batteries (LIBs) to LMBs. This study precisely regulations the crystal structure of β-polypropylene and separator porous construction to investigate the intrinsic porous structure and mechanical properties determined electrochemical performances and cycling durability of LMBs. Crystal structure characterizations, porous structure analyses, and electrochemical cycling tests uncover appropriate annealing thermal stimulation concentrates β-lamellae thickness and enhances lamellae thermal stability by rearranging molecular chain in inferior β-lamellae, maximally homogenizing biaxial tensile deformation and resultant porous constructions. These even pores with high connectivity lower ion migration barriers, alleviate heterogeneous Li+ flux dispersion, stabilize reversible Li plating-stripping behaviors, and hinder coursing and branching of Li dendrites, endowing steady cell cycling durability, especially at higher currents due to the highlighted uncontrollable cumulation of dead Li, which offers new insights for the current pursuit of high-power density battery and fast charging technology. The suggested separator structure-chemical nature functions in ensuring cyclic cell stability and builds reliable relationships between separator structure design and practical LMBs applications.

The development of efficient metal-zeolite bifunctional catalysts for catalytic fast pyrolysis (CFP) of biomass waste is highly desirable for bioenergy and renewable biofuel production. However, conventional metal-loaded zeolites often suffer from metal sintering during pyrolysis and are thus inactivated. In this study, single-site Ga-functionalized hollow ZSM-5 (GaOx@HS-Z5) was synthesized via an impregnation-dissolution-recrystallization strategy without H2 reduction. The Ga atom was coordinated to four oxygen atoms in HS-Z5 frameworks. Benefitting from the highly dispersed single-Ga atoms and hollow zeolite framework, 3GaOx@HS-Z5 performed the best in producing hydrocarbon-rich bio-oil compared to impregnated 3GaOx/HS-Z5 and H2-reduced 3Ga@HS-Z5 in the maize straw CFP. In particular, 3GaOx@HS-Z5 delivered the highest bio-oil yield (23.6 wt%) and hydrocarbon selectivity (49.4 area%). 3GaOx@HS-Z5 also retained its structural integrity and catalytic activity after five pyrolysis-regeneration cycles, demonstrating its advantage in practical biomass CFP. The elimination of H2 reduction during the synthesis of catalyst provides an additional advantage for simplifying the CFP process and reducing operating costs. The retained Ga micro-environment and anti-sintering properties were unique for 3GaOx@HS-Z5, as severe metal sintering occurred during pyrolysis for other metals (e.g., NiOx, ZnOx, FeOx, and CoOx) that encapsulated HS-Z5.

Direct methanol fuel cells (DMFCs) have attracted extensive attention as promising next-generation energy conversion devices. However, commercialized proton exchange membranes (PEMs) hardly fulfill the demand of methanol tolerance for DMFCs employing high-concentration methanol solutions. Herein, we report a series of semi-crystalline poly(arylene ether ketone) PEMs with ultra-densely sulfonic-acid-functionalized pendants linked by flexible alkyl chains, namely, SL-SPEK-x (where x represents the molar ratio of the novel monomer containing multiple phenyl side chain to the bisfluoride monomers). The delicate structural design rendered SL-SPEK-x membranes with high crystallinity and well-defined nanoscale phase separation between hydrophilic and hydrophobic phases. The reinforcement from poly(ether ketone) crystals enabled membranes with inhibited dimensional variation and methanol penetration. Furthermore, microphase separation significantly enhanced proton conductivity. The SL-SPEK-12.5 membrane achieved the optimum trade-off between proton conductivity (0.182 S cm−1, 80 °C), water swelling (13.6%, 80 °C), and methanol permeability (1.6 × 10−7 cm2 s−1). The DMFC assembled by the SL-SPEK-12.5 membrane operated smoothly with a 10 M methanol solution, outputting a maximum power density of 158.3 mW cm−2, nearly twice that of Nafion 117 (94.2 mW cm−2). Overall, the novel structural optimization strategy provides the possibility of PEMs surviving in high-concentration methanol solutions, thus facilitating the miniaturization and portability of DMFC devices.

Although lithium-sulfur batteries (LiSBs) are regarded as one of the most promising candidates for the next-generation energy storage system, the actual industrial application is hindered by the sluggish solid-liquid phase conversion kinetics, severe shuttle effect, and low sulfur loadings. Herein, a zeolitic imidazolate framework (ZIF) derived heterogeneous ZnSe-CoSe nanoparticles encapsulated in hollow N-doped carbon nanocage (ZnSe-CoSe-HNC) was designed by etching with tannic acid as a multifunctional electrocatalyst to boost the polysulfide conversion kinetics in LiSBs. The hollow structure in ZIF ensures large inner voids for sulfur and buffering volume expansions. Abundant exposed ZnSe-CoSe heterogeneous interfaces serve as bifunctional adsorption-catalytic centers to accelerate the conversion kinetics and alleviate the shuttle effect. Together with the highly conductive framework, the ZnSe-CoSe-HNC/S cathode exhibits a high initial reversible capacity of 1305.3 mA h g−1 at 0.2 C, high-rate capability, and reliable cycling stability under high sulfur loading and lean electrolyte (maintaining at 745 mA h g−1 after 200 cycles with a high sulfur loading of 6.4 mg cm−2 and a low electrolyte/sulfur ratio of 6 μL mg−1). Theoretical calculations have demonstrated the heterostructures of ZnSe-CoSe offer higher binding energy to lithium polysulfides than that of ZnSe or CoSe, facilitating the electron transfer to lithium polysulfides. This work provides a novel heterostructure with superior catalytic ability and hollow conductive architecture, paving the way for the practical application of functional sulfur electrodes.

Microbial fuel cells (MFCs) are a well-known technology used for bioelectricity production from the decomposition of organic waste via electroactive microbes. Fat, oil, and grease (FOG) as a new substrate in the anode and microalgae in the cathode were added to accelerate the electrogenesis. The effect of FOG concentrations (0.1%, 0.5%, 1%, and 1.5%) on the anode chamber was investigated. The FOG degradation, volatile fatty acid (VFAs) production, and soluble chemical oxygen demand along with voltage output kinetics were analyzed. Moreover, the microbial community analysis and active functional enzymes were also evaluated. The maximum power and current density were observed at 0.5% FOG which accounts for 96 mW m−2 (8-folds enhancement) and 560 mA m−2 (3.7-folds enhancement), respectively. The daily voltage output enhanced upto 2.3-folds with 77.08% coulombic efficiency under 0.5% FOG, which was the highest among all the reactors. The 0.5% FOG was degraded >85%, followed by a 1% FOG-loaded reactor. The chief enzymes in β-oxidation and electrogenesis were acetyl-CoA C-acetyltransferase, riboflavin synthase, and riboflavin kinase. The identified enzymes symbolize the presence of Clostridium sp. (>15%) and Pseudomonas (>10%) which served as electrochemical active bacteria (EAB). The major metabolic pathways involved in electrogenesis and FOG degradation were fatty acid biosynthesis and glycerophospholipid metabolism. Utilization of lipidic-waste (such as FOG) in MFCs could be a potential approach for simultaneous biowaste utilization and bioenergy generation.

Lithium–sulfur (Li–S) batteries have attracted wide attention for their high theoretical energy density, low cost, and environmental friendliness. However, the shuttle effect of polysulfides and the insulation of active materials severely restrict the development of Li–S batteries. Constructing conductive sulfur scaffolds with catalytic conversion capability for cathodes is an efficient approach to solving above issues. Vanadium-based compounds and their heterostructures have recently emerged as functional sulfur catalysts supported on conductive scaffolds. These compounds interact with polysulfides via different mechanisms to alleviate the shuttle effect and accelerate the redox kinetics, leading to higher Coulombic efficiency and enhanced sulfur utilization. Reports on vanadium-based nanomaterials in Li–S batteries have been steadily increasing over the past several years. In this review, first, we provide an overview of the synthesis of vanadium-based compounds and heterostructures. Then, we discuss the interactions and constitutive relationships between vanadium-based catalysts and polysulfides formed at sulfur cathodes. We summarize the mechanisms that contribute to the enhancement of electrochemical performance for various types of vanadium-based catalysts, thus providing insights for the rational design of sulfur catalysts. Finally, we offer a perspective on the future directions for the research and development of vanadium-based sulfur catalysts.

The photoelectrochemical conversion of CO2 into value-added products emerges as an attractive approach to alleviate climate change. One of the main challenges in deploying this technology is, however, the development and optimization of (photo)electrodes and photoelectrolyzers. This review focuses on the fabrication processes, structure, and characterization of (photo)electrodes, covering a wide range of fabrication techniques, from rudimentary to automated fabrication processes. The work also highlights the most relevant features of (photo)electrodes, with special emphasis on how to measure and optimize them. Finally, the article analyses the integration of (photo)electrodes in different photoelectrolyzers architectures, analyzing the most recent research work that comprises photocathode, photoanode, photocathode-photoanode, and tandem photoelectrolyzers configurations to ideally achieve unbiased CO2 conversion systems. Overall, comprehensive guidelines are provided for future advancements in developing effective devices for CO2 conversion, bridging the gap towards the use of sunlight as the unique energy input and practical applications.

Steam reforming (SR) of fossil methane is already a well-known, documented and established expertise in the industrial sector as it accounts for the vast majority of the global hydrogen production. From a sustainable development perspective, hydrogen production by SR of biomass-derived feedstock represents a promising alternative that could help to lower the carbon footprint of the traditional process. In this regard, bio-alcohols such as methanol, ethanol or glycerol are among the attractive candidates that could serve as green hydrogen carriers as they decompose at relatively low temperatures in the presence of water compared to methane, allowing for improved H2 yields. However, significant challenges remain regarding the activity and stability of nickel-based catalysts, which are most widely used in alcohol SR processes due to their affordability and ability to break C–C, O–H and C–H bonds, yet are prone to rapid deactivation primarily caused by coke deposition and metal particle sintering. In this state-of-the-art review, a portfolio of strategies to improve the performance of Ni-based catalysts used in alcohol SR processes is unfolded with the intent of pinpointing the critical issues in catalyst development. Close examination of literature reveals that the efforts tackling these recurring issues can be directed at the active metal, either by tuning Ni dispersion and Ni-support interactions or by targeting synergistic effects in bimetallic systems, while others focus on the support, either by modifying acid-base character, oxygen mobility, or by embedding Ni in specific crystallographic structures. This review provides a very useful tool to orient future work in catalyst development.

Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO2 methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating. By adjusting the reaction conditions, the catalyst is able to perform CO2 methanation reaction under autothermal process operated inside a non-adiabatic reactor, without any external energy supply. Such autothermal process is possible thanks to the high apparent density of the UOx which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out. Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor, where complete insulation is required to prevent heat disequilibrium, in order to reduce as much as possible, the heat exchange with the external medium. The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation. It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.

Under the new energy resource structure, electrocatalysts are key materials for the development of proton membrane fuel cells, electrolysis of aquatic hydrogen devices, and carbon dioxide reduction equipment, to address energy shortages and even environmental pollution issues. Although controlling the morphology or doping with heteroatoms for catalyst active centers have accelerated the reaction rate, it is difficult to solve the problems of multiple by-products, and poor stability of catalytic sites. From this, it will be seen that single regulation of metal active centers is difficult to comprehensively solve application problems. Orderly assembly and coordination of catalyst multi-hierarchy structures at the mesoscale above the nanometer level probably be more reasonable strategies, and numerous studies in thermal catalysis have supported this viewpoint. This article reviews the multi-hierarchy design of electrocatalyst active centers, high-energy supports, and peripheral structures in recent years, providing unconventional inspiration about electrocatalyst creation, which perhaps serves as a simple tutorial of electrocatalysis exploration for abecedarian.

Scaled-up industrial water electrolysis equipment that can be used with abundant seawater is key for affordable hydrogen production. The search for highly stable, dynamic, and economical electrocatalysts could have a significant impact on hydrogen commercialization. Herein, we prepared energy-efficient, scalable, and engineering electronic structure modulated Mn-Ni bimetal oxides (Mn0.25Ni0.75O) through simple hydrothermal followed by calcination method. As-optimized Mn0.25Ni0.75O displayed enhanced oxygen and hydrogen evolution reaction (OER and HER) performance with overpotentials of 266 and 115 mV at current densities of 10 mA cm−2 in alkaline KOH added seawater electrolyte solution. Additionally, Mn-Ni oxide catalytic benefits were attributed to the calculated electronic configurations and Gibbs free energy for OER, and HER values were estimated using first principles calculations. In real-time practical application, we mimicked industrial operating conditions with modified seawater electrolysis using Mn0.25Ni0.75O∥Mn0.25Ni0.75O under various temperature conditions, which performs superior to the commercial IrO2∥Pt-C couple. These findings demonstrate an inexpensive and facile technique for feasible large-scale hydrogen production.